fixed null issue in tests
fixed null issue in tests

georgemarshall/DefinitelyTyped,mcliment/DefinitelyTyped,georgemarshall/DefinitelyTyped,georgemarshall/DefinitelyTyped,dsebastien/DefinitelyTyped,borisyankov/DefinitelyTyped,georgemarshall/DefinitelyTyped,borisyankov/DefinitelyTyped,markogresak/DefinitelyTyped,dsebastien/DefinitelyTyped